Automatic control apparatus for aircraft



Jan. 12, 1943. Fjw. MEREDITH 2,307,941

AUTOMATIC CONTROL APPARATUS FOR AIRCRAFT Filed July 7, 1939 3'Sheets-Sheat l Jan. 12,1943. F. w. MEREDITH AUTOMATIC- CONTROL APPARATUS FOR AIRCRAFT Filed July 7. 1939; 3 Sheets-Sheet 2 Jan. 1943' F. (MEREDITH 2,307,941

AUTOMATIC CONTROL APPARATUS FQR AIRCRAFT Filed July '7. 1939 3 Sheets-Sheet 3 manta at. 12, 1943 Aprons-no oomonmsna'rns ron nmcasr'r Frederick William assignor to B.

Meredith. lnndont Enlll l. Smith a; Sons (Motor Accessories) Limited, London, a British Application in, 7, mo. Serial No. 283,314

. In Great Britain my 1:, ms

14 cums. (or 244-19) This invention relates to automatic control apparatusfor aircraft and is concerned with such control apparatus having an azimuth gyroscope or other turn indicator controlling the rudder of the aircraft, together with means for changing the course. The object of the present invention is to provide an improvement of such apparatus such as to enable banked turns to be performed in a simple manner.

According to the present invention thereis provided a control apparatusv for aircraft comprising means for detecting turn of the aircraft in azimuth and controlling the course of the aircraft according to detected turn in order to maintain a given course (e. g. by control of the rudder), means for changin the course and means responsive to lateral acceleration or sidea slip operating said means for changing course for the purpose of control of the lateral acceleration or side-slip when the craft is banked. Thus,

with the apparatus in operation, in order to change course it is only necessary to bank the craft to the desired angle and the rudder or the like will be automatically actuated to suppress.

side-slip and a correctly banked turn will be performed. According to a feature of the invention means is provided for displacing the datum of the means responsive to lateral acceleration or sideslip.

According to another feature of the invention bank setting means for the purpose of effecting a turn is coupled with the said means for displacing the datum of the means responsive to lateral acceleration or side-slip.

A further feature of the inventionconsists in that the means for changing course is also op-- erated by bank setting means.

Another feature of the invention consists in the provision of means controlled by the bank setting means for rendering said course changing means inoperative for the purpose of ensuring straight flight.

In one construction the means for detectin the turn of the aircraft comprises an azimuth gyroscope controlling a servo-motor for actuating the rudder and having precessing means. which precessing means is controlled by the means responsive to lateral acceleration or sideslip.

In another construction the means for detectjustable under the control of the means responsive to lateral acceleration or side-slip.

Specific embodiments of the invention are illustrated diagrammatically by way of example in the accompanying drawings, in which:

Figure 1 is a general view of a gyroscopic control apparatus for aircraft; I

Figures 2 and 3 are detail views of the apparatus shown in Figure 1, and

Figure 4 shows a modified construction of the which th frame I! can turn. is horizontal and ing turn of the aircraft comprises an azimuth gyroscope controlling a servo-motor for actuating the rudder, with the provision of follow-up mechanism, and the follow-up mechanismis adto not h wn.

lengthwise of the craft. The platform II is guided for movement about the axis Y by a column It engaging in a slot Ii in an arcuate guide I! pivoted about an axis which coincides with the Y axis when the frame 12 is in the horizontal position.

The platform ll carries a gyroscope I for controlling the craft in pitch, this gyroscope comprising a rotor ll whose axis of spin is horizontal and lies fore-and-aft of the'craft. The

rotor It is carried in bearings in a gimbal ring I! arranged horizontally and in turn pivotally mounted in an outer gimbal ring 20 which is rotatable about a vertical axis on the platform ii. The inner gimbal ring I! is connected by a link 2| to a valve 22 which controls a supply of air under pressure to a servo-motor, not shown, for adjusting the elevator of the aircraft in known manner. The outer gimbal ring I! is' un-- balanced by a weight 23 and it is connected by a link 24 to a valve 25 controlling a supply of air under pressure to a servo-motor, not shown, for operating the rudder in known manner.

Also mounted on the platform II is a gyroscope 200 for controlling the ailerons of the aircraft. This gyroscope comprises a rotor 30 whose axis of spin is horizontal and lies transversely of the aircraft. The rotor is carried in bearings in an inner gimbal-ring Ii, the plane of which also lies transversely of the aircraft and this inner gimbal ring is pivotally mounted inan outer gimbal ring 32 which is pivoted for movement about a fore-and-aft horizontal axis On the platform It. The outer gimb al ring I! is connected by a link It to a valve 34 controlling the supply of air under pressure to a servofor operating the ailerons of the aircraft. The inner gimbal ring 3| is con-.

pressure in the conduit leading from the nozzle 42. The blade 45 is mounted on a weight 44 which is carried by means of springs 45 connected to a member 45 mounted on a spindle 41 rotatable in the frame |2 about the X axis. The member 48 also carries an electric contact brush 48 cooperating with a commutator 49 on the frame |2, this frame having interconnected contacts 50 and 5| separated by an insulating section 52.

The brush 48 normally rests on this insulating section.

The brush 48 is connected through a battery indicated at 53 to one terminal of an electroand one of the contacts 50, 5|, so that the valve magnet 54 of which the other terminal is connected to the contacts 50 and 5|. An armature 55 controlled by the magnet 54 is connected to the spindle 56 of a change-over valve 51.

The valve 51 has an inlet 58 which is connectedto the nozzle 42 and another inlet 59 to which air under pressure is applied through a reducing valve 80. According to the position of the blade 43 between the nozzles 4|. and 42 the air pressure applied from the nozzle 42 to the valve varies within a range extending above and below the pressure applied at the inlet 59. The valve has outlets 62 leading to a bank trimming motor 10 carried on the platform i0 and having an operating link 1| connected to the inner gimbal ring 3| or the gyroscope 7.00. The valve has other outlets 12 leading to an azimuth precessing motor 51 applies the air pressures at the inlets 58 and 59 to the azimuth precessing motor I3. The motor transmits a torque to the inner gimbal ring l9,

causing the rotor to precess. The resulting pre- I cessional movementrofthe outer gimbal ring 20 operates the valve 25 to energise the servo-motor for moving the rudder to turn the aircraft in such a sense as to limit the side-slip causing the said displacement of the blade 43.

Thus .the weight 44, its associate jets 4| and. 42 and the azimuth precessing motor 13 together form a governor to control the extent of side slip. In the operation of the apparatus as thus far described, there will be a side-slip associated with any turn and proportional .to the rate of the turn. To reduce this error, as shown in Figure 3, the line of the jets 4| and 42 is displaced above the axis of rotation of the frame |2, so that when the frame I2 is inclined about its axis X, to inltiate a turn, the jets are displaced relative to the blade 43 even though the side-slip is zero.

In straight flight the contact 48 is open and the pressure difference in the conduits 58 and 59 is applied to the bank trimming motor 10 for the purpose of ensuring correct levelling of the platform l0 about the axis X. Thus if the platform iii is slightly tilted about the X axis the blade 43"is displaced relative to its associated jets and the pressure in the conduit 58 is no longer equal to pressure in the conduit 59 and so 13 having an operating link 14 connectedto the inner gimbal ring l9 of the rudder and elevator gyroscope I00. In the energised position of the magnet 54 the movable element 53 of the valve is in such position as to connect the inlets 58 and 59 to the processing motor 13 and in the deenergised position the trimming motor 19. The

blade 43 has one edge normally lying across the centre of the nozzle 4| so that the difference in pressure at the inlets 58 and 59 of the valve has a zero value at the normal-position and an increasing value upon relative movement of the blade and the nozzles and depending in sign upon the direction of this relative movement.

By means of the apparatus according to this invention the control of the aircraft in pitch and roll is effected by mean such as the pulley and cable 80 for turning the platform about the X axis, and another pulley and cable 8i for turning-the platform about the Y axis. By rotation of the platform It about the Y axis it is displaced from its horizontal position in the aircraft so as to produce by means of the gyroscope I00 a corresponding change in the elevational directicn of the aircraft. Similarly, by rotation of the platform It about the X axis, displacing it from the horizontal position in the aircraft, there is that the motor 10 applies a torque to the inner gimbal ring 3|, so as to precess the outergimbal ring 32 to change the attitude of the craft until the platform H) is correctly levelled about the X axis.

By adjustment of the pitch control 8| the platform I0 is displaced relative to the gyroscope I08 v about the axis of the inner gimbal ring and the consequential relative movement of this inner gimbal ring andthe platform I0 controls the valve to produce a movement of the elevators to tilt the craft so that the platform is returned to the horizontal position. If however the platform i0 is slightly tilted about the Y axis .the weight 23 applies a torque to the outer gimbal ring 20 which precesses the inner gimbal ring l9 thus changing the attitude of the craft'until the platform is correctly'levelled about the Y axis.

It will thus be appreciated that the platform ID on which the gyroscopic devices are mounted is always returned to the horizontal position regardless of the trim of the aircraft so that in the case of each gyroscope the axis of precession during a turn is maintained vertical and thus lies in the same vertical plane as the rotor axis.

The bracket 46 which carries the electric contact brush 48 is mounted on a spindle 41 which is normally fixed with respect to the frame i2. It may, however, be rotated through a pulley 82 and cable for producing a flat turn of the air craft, in which case the pulley is held fixed.

In other respects the gyroscopes I08 and 200 perform their well known functions, operating in the known manner for the control of the rudder and elevators and the control of the ailerons respectively. for instance, as described in Great peripheral groove I23 of the distributor.

gyroscope I which detects turn of the aircraft in azimuth. In the construction above described,

change of course is efiected by the precessing motor 13 which is automatically actuated by the means responsive to lateral acceleration consisting of the sprung-weight 44 and its associated Jets.

In alternative construction as shown, in Figure 4, the change of course is effected by rotamaintains the aircraft on its course. The followup mechanism which includes the differential gear element I30 and planetary system I04 is displaced by rotation of the other element I33 of a the differential gear. Should lateral acceleration or side-slip occur, a difference in air pressure is produced at the nozzles I43 and I40 due to the ac- 4 tion of the pendulum 44 and the rotor I43 is tion of side-slip. The rotor I43 thus drives tion of the frame in which the gyroscope is v mounted.

Referring to Figure 4, there is shown an azimuth gyroscope for control of course which has a rotor IIII arranged withits axis of spin horizontal and mounted to rotate in a horizontal gimbal ring I I I which is in turn pivotally mounted in an azimuth or outer gimbal ring III. The

outer gimbal ring H2 is rotatably mounted in a a bracket II3 rigid with a worm-wheel H4 and is connected by means of a link I II to a piston valve H8 movable in a valve cylinder III carried by the bracket H3.

The worm-wheel II4 iscarried on a cylindrical distributing member III rotatably mounted in a block II! which is fixed in the aircraft. An inlet pipe I and outlet'pipes HI and I22 for the valve cylinder I I1 pass into the distributing member H8 and communicate respectively with peripheral grooves I23, I24 and I2! therein. Pipes I26 and I2! carried in the block III communicate with the grooves I24 and I20 respectively and serve to apply air under pressure to opposite ends of a servo-motor cylinder I24, the air under pressure being supplied through a pipe I23 to the The piston rod I30 of the servo-motor is coupled to the rudder for its automatic control.

To provide a follow-up the piston rod I30 carries arack I 3| meshing with a gear-wheel I32. The gear-wheel I32 is mounted on a spindle I33 in driving engagementwith the planetary system I34 of a diiferential gear. One element II! of this gear is mounted on a spindle Iflcarrying a worm I31 meshing with the worm-wheel II4 so that assuming the other element I30 of the differentialgear to be fixed a follow-up isobtained by rotation of the worm-wheel II4.

The element I30 of the differential gear is mounted on a spindle I30 carrying a worm-wheel I40 with which meshes a worm I. The warm I is-driven through a reduction gear train I42 by an air driven rotor I43 which is driven by air jets from two nozzles I43 and I4! arranged so as to cause theair to impinge on the blades of the rotor I43 in the directions tending to rotate the rotor in opposite directions. The difference in air pressure applied to these two nozzles is controlled by means sensitive to lateral acceleration, for example, in the same way as the pressure difference in the lines 12 (Figure'l) is controlled by the sprung-weight 44 and its associated Jets.

In this case the change-over valve 01 may be electrically operated under the control of contacts such as contacts 48, I0 and II (Figure 1) so ar-' ranged as to be operative as hereinbefore described when it is desired to bank'the'aircraft.

In use of the apparatus the gyroscope controls driven in a direction depending upon the directhrough the reduction gear I42 and worm-wheel I and I40 the element I38 of the differential gear, to displace the follow-up, as aforesaid. In this manner, the rudder is actuated to suppress lateral acceleration or side-slip when the craft is banked for the purpose of making a turn. Thus, to change the course of the aircraft it is only necessary to bank the craft to the naked angle and the rudder will be automatically actuated to suppress side-slip and a correctly banked turn will be performed.

It will be understood that the invention is not limited to the specific constructions hereinbefore described which may be modified, for example,

by the use of means other than a sprung-weight for detecting lateral acceleration or side-slip of the aircraft.

I claim:

1. Control apparatus for aircraft comprising means for controlling thecourse of the aircraft, means for detecting turn of the aircraft in azimuth, means controlled by said detecting means and connected to act on said course control means to maintain a given course, means for changing course, said course changing means being connected to actuate said course control means, and means responsive to lateral acceleration and connected to actuate said course changing means for controlling lateral acceleration when the aircraft is banked.

2. Control apparatus for aircraft comprising means for controlling the rudder of the aircraft, means for detecting turn of the aircraft in azi- I muth, means controlled by said detecting means and connected to act on said rudder control means to maintain a given course, means for changing course, said course changing means being connected to actuate said rudder control means, and means rekponsive to lateral acceleration and connected to actuate said course changing means for controlling lateral acceleration when the aircraft is banked. 3. Control apparatus for aircraft comprising means for controlling the course of the aircraft,

means for detecting turn of the aircraft in azimuth, means controlled by said detecting means and adapted to actuate said course control means to maintain a given course, means for changing course, said course changing means being connected to actuate said course control. means, means responsive to lateral acceleration, constructed for displacement from a datum and connected to actuate said course changing means for controlling lateral acceleration when the aircraft is banked, and means for displacing the datum of said. means responsive to lateral acceleration.

4. Control apparatus for aircraft comprising I means for controlling the course of the aircraft,

means for detecting turn of the aircraft in azimuth, means controlled by said detecting means and adapted to actuate said course control means to maintain a given course, means for changing course, said course changing means being connected to actuate said course control means, bank setting means for effecting a banked turn, means responsive to lateral acceleration, constructed for displacement from a datum and connected to actuate said course changing means for controlling lateral acceleration when the aircraft is banked, and means coupling said bank setting means to said means for displacing said datum.

5. Control apparatus for aircraft comprising means for controlling the course of the aircraft, means for detecting turn of the aircraft in azimuth, means controlledby said detecting means and adapted to actuatesaid course control means to maintain a given course, means for changing course, said course changing means being connected to actuate said course control means, bank setting means for effecting a banked turn, means responsive to lateral acceleration, constructed for displacement from a datum and connected to actuate said course changing means for controlling lateral acceleration when the aircraft is banked, and means coupling said bank setting means to said means for displacing said datum, said bank setting means being connected to actuate said course'changing means.

,6. In combination with the apparatus defined in claim 4, means connected for control by said bank setting means for rendering said course changing means inoperative for ensuring straight flight.

7. In combination with the apparatus defined in claim 5, means connected for control by said bank setting means for rendering said course changing means inoperative for ensuring straight flight.

8. Control apparatus for aircraft comprising a rudder, an azimuth gyroscope and associated means for detecting turn, means including a servo-motor connected to said turn detecting means for actuating saidrudder, follow-up mechanism for said servo-motor, and means responsive to lateral acceleration connected for automatically adjusting said follow-up mechanism to control the lateral acceleration when the aircraft is banked. i

9. A control apparatus for aircraft having a vertical rudder, comprising means for detecting turn of the aircraft in azimuth, means controlled by said means for detecting turn to operate the rudder to maintain a given course,'means for changing said course, bank setting means for controlling the aircraft in roll, and means responsive to lateral acceleration or side-slip operating said means for changing course to control lateral acceleration or side-slip when the aircraft is banked, whereby a turn of the aircraft is effected by operation of said bank setting means.

10. A- control apparatus for aircraft having a vertical rudder, comprising means for detecting turn of the aircraft in azimuth, means controlled by said means for detecting tum to operate the rudder to maintain a given course, bank setting means fo controlling the aircraft in roll, means for changing said course, means operated by said bank settin means to render the means for changing course operative, and means responsive to lateral acceleration or side-slip operating said means for changing-course to control the lateral acceleration or side-slip when the aircraft is banked by said bank setting means, whereby a turn of the aircraft is effected by operatiori of said bank setting means.

11. A control apparatus for aircraft having a vertical rudder, comprising means for detecting turn of the aircraft in azimuth, means controlled by said means for detecting turn to operate the rudder to maintain a given course, means for changing said course, bank setting means for motor for actuating the rudder of the aircraft,

means controlled by said gyroscope according to said detected turn for controlling said servomotor, precessing means for said gyroscope to vary its datum for detected turn, bank setting means controlling the aircraft in roll, and means responsive to lateral acceleration l or side-slip controlling said precessing means to reduce lateral acceleration or side-slip by the application of rudder when the aircraft is banked, whereby a banked turn of the aircraft is effected bycontrol of said bank setting means.

13. A control apparatus for aircraft having a vertical rudder, v comprising an azimuth yroscope for detecting turn of the aircraft, a servomotor for actuating the rudder of the aircraft, means controlled by said gyroscope according to detected turn for controlling said servo-motor,

a follow-up mechanism for said servomotor. which follow-up mechanism is adjustable to vary the datum for detected turn, bank setting means for controlling the aircraft in roll, and means responsive to lateral acceleration or side-slip for automatically adjusting said follow-up mechanism to reduce the lateral acceleration or sideslip when the aircraft is banked, whereby a 'banked turn of the aircraft is effected by control of said bank setting means.

14. A course controlling apparatus for an air craft comprising an adjustable course setting device, a rudder control, means for detecting turn of theaircraft in azimuth and associated with said rudder control to maintain the course initially set by said setting device, a banking control, a side slip detector operatively connected with said adjustable course setting device, and arranged to set it to a new course in accordance with the side slip occasioned when the banking control is operated, the rudder thus being moved by said turn detecting means in an endeavor to maintain the initial course and to correct deviation produced by banking.

FREDERICK WILLIAM MEREDITH. 

